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Macarthur | Posted in Energy Efficiency and Durability on

I live in northern Wisconsin and was recently gifted sheets of 3” white foam board. I assume these are EPS and wondering if I should use these for attic or basement insulation.
Our attic sits above our garage, and is attached. Currently, our attic is insulated with about 20-25” of blown in cellulose insulation up to the space above the garage. When we were insulating we ran out of the cellulose in the city, and I have not done anything with it since. Our garage is not heated, but since it is attached to the house I was wanting to give it some insulation. However, my concern is if I insulate incorrectly in the attic there could be condensation in the trusses and ultimately mold, etc. 
the other option is insulating our unfinished basement with the foam board prior to putting studs up. Any recommendations on either as a good or bad option?

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  1. adrienne_in_nj | | #1

    Congratulations on that nice gift! Use it in the basement. You will have a nice continuous layer of insulation behind the studs. There is no point in insulating the attic above an unconditioned garage. It’s a complete waste of materials.

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